Flexible disk drives, also known as floppy disk drives or diskette drives, have the capability of reading or writing magnetic signals on interchangeable flexible disks, which disks are loosely contained in a flexible envelope, or cartridge, for protection (as shown and described, for example, in U.S. Pat. No. 4,193,102). The cartridge has a central aperture through which the central aperture of the disk is exposed, and there also is a head access slot through the envelope so that a recording head can interact with the surface of the disk.
To be able to read or write information on disks interchanged between a number of disk drives, it is required that the disk be precisely registered in each drive in substantially the same position. This is accomplished by centering and clamping each disk to the spindle that rotates the disk. The spindle axis thus becomes the critical reference to which the disk is registered, and the collet, the disk cartridge, and the recording head, or heads, all have critical reference positions relative to the spindle axis.
The flexible disk is centered and clamped to the spindle by means of a collet. During the colleting operation, the collet penetrates the center aperture of the disk and then enters a recess area in the spindle. The recess in the spindle is matched to the collet so that the collet centers itself to the spindle. As a result, the collet centers the disk to the spindle. Examples of colleting apparatus are shown in U.S. Pat. Nos. 3,768,815, 4,125,883, and 4,409,629.
Typically, the collet is either slidably mounted on a shaft aligned with the spindle axis or is loosely spring mounted. Examples of the former are shown in U.S. Pat. Nos. 3,678,481 and 4,216,510, while examples of the latter are shown in U.S. Pat. Nos. 4,125,883 and 4,193,101. In both types, the collet is positioned so that its axis is substantially aligned with the spindle axis.
The disk cartridge is guided into the disk drive during insertion so that its center is substantially aligned with the spindle axis. This assures that the collet will penetrate the center aperture of the disk and the spindle recess in order to center and clamp the disk on a spindle. However, it is expensive to build the drive such that the cartridge guides and the collet axis are both substantially aligned with the spindle axis due to the number of parts required and the manual adjustments that must be made to obtain alignment with the spindle axis.